diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
new file mode 100644
index 0000000..7fb53e1
--- /dev/null
+++ b/.github/workflows/main.yml
@@ -0,0 +1,40 @@
+name: CI
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up JDK 1.8
+      uses: actions/setup-java@v1
+      with:
+        java-version: 1.8
+    - name: Get current date
+      id: date
+      run: echo "::set-output name=date::$(date +'%Y%m%d%H%M')"
+    - name: Build with Ant
+      run: ant -noinput -buildfile build.xml -Dtimestamp=${{steps.date.outputs.date}}
+    - name: Create Release
+      id: create_release
+      uses: actions/create-release@v1
+      env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      with:
+        tag_name: ${{steps.date.outputs.date}}
+        release_name: ${{steps.date.outputs.date}}
+        draft: false
+        prerelease: false
+    - name: Upload Release Asset
+      id: upload-release-asset 
+      uses: actions/upload-release-asset@v1.0.1
+      env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      with:
+        upload_url: ${{ steps.create_release.outputs.upload_url }}
+        asset_path: dist/CommunityModules-${{steps.date.outputs.date}}.jar
+        asset_name: CommunityModules-${{steps.date.outputs.date}}.jar
+        asset_content_type: application/zip
\ No newline at end of file
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
deleted file mode 100644
index 797c71c..0000000
--- a/azure-pipelines.yml
+++ /dev/null
@@ -1,31 +0,0 @@
-trigger:
- - master
-
-pool:
-   vmImage: 'Ubuntu-16.04'
- 
-steps:
-  - task: Ant@1
-    inputs:
-      buildFile: 'build.xml' 
-      javaHomeOption: 'JDKVersion'
-      jdkVersionOption: '1.8'
-      jdkArchitectureOption: 'x64'
-
-  - task: GitHubRelease@0
-    inputs:
-      gitHubConnection:  CommunityModules
-      #repositoryName: '$(Build.Repository.Name)' 
-      #action: 'create' # Options: create, edit, delete
-      #target: '$(Build.SourceVersion)' # Required when action == Create || Action == Edit
-      tagSource: 'manual' # Required when action == Create# Options: auto, manual
-      tag: '$(Build.BuildNumber)' # Required when action == Edit || Action == Delete || TagSource == Manual
-      #title: # Optional
-      #releaseNotesSource: 'file' # Optional. Options: file, input
-      #releaseNotesFile: # Optional
-      #releaseNotes: # Optional
-      assets: 'dist/CommunityModules-*.jar' # Optional
-      #assetUploadMode: 'delete' # Optional. Options: delete, replace
-      #isDraft: false # Optional
-      #isPreRelease: false # Optional
-      #addChangeLog: true # Optional
diff --git a/build.xml b/build.xml
index 60df739..ed40171 100644
--- a/build.xml
+++ b/build.xml
@@ -6,6 +6,12 @@
 	<property name="lib" location="lib"/>
 	<property name="tests" location="tests"/>
 
+	<tstamp>
+		<format property="timestamp"
+          pattern="yyyyMMdHHmm"
+          locale="en,UK"/>
+	</tstamp>
+
 	<target name="init" description="Create the build and dist directory structure">
 		<mkdir dir="${build}"/>
 		<mkdir dir="${dist}"/>
@@ -25,7 +31,7 @@
 
 	<target name="dist" depends="compile" description="Combine the module overwrites and the TLA+ definitions into a distribution">
 		<tstamp/>
-		<jar jarfile="${dist}/CommunityModules-${DSTAMP}${TSTAMP}.jar">
+		<jar jarfile="${dist}/CommunityModules-${timestamp}.jar">
 			<fileset dir="${build}/"
              includes="**/*.class"/>
 			<fileset dir="${src}/"
@@ -50,7 +56,7 @@
 			<classpath>
 				<pathelement location="${lib}/tla2tools.jar" />
 				<!-- The jar that has just been built by the dist target. -->
-				<pathelement location="${dist}/CommunityModules-${DSTAMP}${TSTAMP}.jar" />
+				<pathelement location="${dist}/CommunityModules-${timestamp}.jar" />
 			</classpath>
 		</java>
 	</target>
diff --git a/modules/IOUtils.tla b/modules/IOUtils.tla
index 3dd486a..17f09b1 100644
--- a/modules/IOUtils.tla
+++ b/modules/IOUtils.tla
@@ -10,3 +10,28 @@ IOSerialize(val, absoluteFilename, compress) == TRUE
 IODeserialize(absoluteFilename, compressed) == CHOOSE val : TRUE
 
 ============================================================================
+
+\* Writes a TLA+ expression to the given file.
+\* TODO: Decide if it should write a module preamble.
+\* Write is easier to implement than Read because it goes from (valid) TLA+
+\* and writes a file whereas Read has to parse it.
+IOWrite(exp, absoluteFilename) == TRUE
+
+\* Reads a TLA+ expression from a file.
+\* TODO: Decide if it reads just a string from a file or expects (valid) TLA+.
+\*         For trace validation it would be preferable to read strings.
+\*       Constant-level expression (what's a use-case to read fileS during state space exploration?
+IORead(absoluteFilename) == TRUE
+
+TLAParse(IORead("C:\\foo\bar"))
+
+(* condition generally of level up to action (but not temporal), e.g. Inv'.  *)
+
+\* Run the given OS command if condition evaluates to true.
+\* This is novel and cannot be done otherwise.
+\* TODO: What to pass to os command? osCommand a string that a user munges directly
+\*       in/with TLA+.
+\*       Can IOWrite/IORead be spec'ed with IOExec?
+IOExec(condition, osCommand) == TRUE
+
+=============================================================================